Almost $50 million of grants were awarded to non-government organisations without proper agreements being put in place, the NSW auditor-general has found.
The payments, totalling $48 million, were made by the Department of Ageing, Disability and Home Care in late June 2009.
Auditor-General Peter Achterstraat has warned that the lack of agreements increases the risk the money will not be properly used and that unspent funds are not being returned to the state.
"Government agencies must have good accounting processes and controls, otherwise errors will be made, money will be misspent and resources poorly utilised," Mr Achterstraat said in a statement.
He said the money had been awarded without following the normal practice, which was designed to ensure the department spent its grants in a "timely manner".
He also found that salary overpayments in the department increased in 2008-09 by 50 per cent to $1.6 million, while money spent on agency staff also increased, to $19.8 million.
Opposition disability services spokesman Andrew Constance said this was money being wasted by the state government which could be used on much-needed services.
"The Rees Labor government's incompetent management of the ageing and disabilities sector has seen millions of dollars wasted that could have gone on improving services," Mr Constance said in a statement.
"The .. government has taken its eye off the disability ball and it's simply not good enough while young people with disabilities are housed in inappropriate care in nursing homes and families are begging for respite accommodation."
The Department of Ageing said it had already taken steps to address the issues raised in the auditor-general's report.
"(The department) is committed to improving accounting processes and financial controls," the department said.